Boiler operating hazards and Preventive Measure

Transcription

1 CHAPTER 18 Boiler Safety compliance Boiler is an important utility in factories. It is used to generate steam. The generated steam is distributed through pipes to feed various equipment in the factory. Poorly maintained boilers can be a potential source of serious accidents. There are several examples of boiler explosion and loss of lives and assets. In a recent boiler explosion in a South Asian country, several floors of a garment factory collapsed, killing about 200 workers. Boilers vary in size, capacity and technology. Smallest boilers are portable and pose a limited risk. Very large boilers have potentially greater risk if not handled appropriately. Thus, factories deploying smaller boilers will need basic and simple measures to ensure safety. However, factories using large boiler plants will require extensive safety procedures. The code of conduct requires proper running and maintenance of boilers. The local law in most countries provides for specific guidelines with regard to boilers. Local regulations may require factories to obtain a license for large capacity boilers. Boiler operating hazards and Preventive Measure It is important to follow the manufacturers instructions, local boiler safety rules and regulations to avoid accidents from boilers. Neglecting safety in boiler operation can lead to loss of lives and assets. The table below provides a very general guideline of possible hazards associated with boiler operation. The manufacturers manual should be referred for safe operation of a specific equipment.

2 , Fig. 5: Preventive Measure For Boiler Safety OPERATING HAZARD POSSIBLE CAUSES LIKELY EFFECT OIL FIRING: High fuel temperature Improper setting of thermostat. Steam control valve stuck open in steam heater. Electrical supply contacts welded closed in electrical heater explosion. Oil gasification. Poor atomization. Unstable flame. Fireside explosion. Fire. Damage to boiler and assets damage. Loss of life or injury. Periodic check of heaters and controls. Low fuel temperature Faulty heater element. Low setting of oil temperature control. Steam supply disrupted or closed. Electric power of heater off. Explosion. Smoky fire. Poor atomization. Discharge of unburned oil in the furnace. Fireside explosion Fire. Damage to boiler and assets damage. Loss of life. Periodic checks of oil temperature and heaters. Wet steam during atomizing Steam line not insulated. Steam traps not working. Steam wet from source. Explosion. Smoky fire. Poor atomization. Sparkles in flame. Unburned oil discharged in furnace. Fireside explosion. Fire. Damage to boiler and assets. Loss of life. Ensure insulation of steam lines. Periodic check of trap operation Low steam pressure Improper setting of control valve. Supply line valves inoperative or not open. Low supply pressure. Explosion. Smoky fire. Poor atomization. Unburned oil discharged in furnace. Fireside explosion. Fire. Damage to boiler and assets. Loss of life and/ or injury to personnel. Insulate all steam lines. Check proper trap operation periodically. Follow manufacturer s instructions. Worn or damaged atomizer Normal wear and tear. Abrasive material in oil. Burner tip not serviced. Explosion. Incomplete combustion. Flare back. Fire. Regular service of tips. Gaskets should be replaced when cleaning or replacing tips. GAS FIRING: Gas line leaks Improperly assembled joints. Excessive pressure. Leaking gasket. Damage to piping, valves and fittings carrying fuel. Explosion. Asphyxiation. Fire. Ensure adequate ventilation. Piping, valves and fittings should be well maintained. Test of leaks and safety devices before operation.

3 OPERATING HAZARD POSSIBLE CAUSES LIKELY EFFECT Gas Line Repair Damage Piping or valves Explosion. Fire. Loss of life or injury. Damage to assets. Accepted methods of r purging and recharging gas lines should be used High Gas pressure Defective gas pressure regulation. Fuel rich mixture. Fireside explosion. Fire. Loss of life or injury. Damage to boiler and assets. Monitor for regulator operation. Check operation and setting of pressure switch periodically. Repair or replace defective regulators and switches. STEAM LEAKS Steam Leaks Damaged or corroded pipes and pressure parts Severe burns. All joints and pipes should be secured. HOT FLY ASH Accumulations of hot fly ash and fly ash in boiler flues and plenums. Workers stepping on hot fly ash. Fly ash may retain heat for several weeks. No visible difference between hot and cold fly ash. Explosive effect of water on hot fly ash. Serious burn injury Warnings to all workers about potential hazard. Allow sufficient cooling time before walking on fly ash. Hot fly ash should be removed with caution using equipment. Water should be sprayed on hot fly ash. STEAM EXPLOSION Low water level Defective low water cutoff or low water cutoff bypassed. Improper water column blow down procedure. Tampering with low water control. Defective boiler water feed system. Defective or inoperative gauge glass. Operator error. Overheated boiler surfaces. Ruptured boiler. Loss of life and/or injury to personnel. Asset damage. Periodic verification of boiler water feed system. Periodic check of low water cut-off operation. Water column blow down procedures should be correct. Do not tamper with low water controls. Replace defective low water controls. Periodic inspection of equalizing lines. Operators should be trained properly. Defective safety valves. Obstruction between boiler and valves. Damaged or corroded valve. Level tied down. Valve outlet obstructed. No release of excess pressure. Excessive pressure on the boiler. Boiler ruptured. Loss of life and injury. Damage to assets. Promptly replace or repair safety valve. Remove obstructions. Periodic test of safety valves.

4 OPERATING HAZARD POSSIBLE CAUSES Defective steam pressure gauges. Broken gauge or poor calibration of gauge. The line from boiler to gauge blocked. Gauge cock is closed. Conflict of multiple gauges. LIKELY EFFECT Gauge will not show the correct pressure even when the boiler is under excessive pressure. The operator will not be aware of true operating conditions. The gauge should be calibrated regularly. Defective gauges should be preplaced promptly. Periodic inspection of gauge connection and piping to boiler for blockage or closed cock. Scaling or corrosion in boiler s internal surfaces. Poor maintenance and test methods. Improper chemical cleaning. Improper water treatment and contaminated boiler water. Poor feed water control. Ruptured boiler due to overheating. Loss of life or injury to workers. Assets damage. Regular maintenance and inspections. Keep maintain log. Boiler water treatment should be appropriate Bypassed controls. Defective electrical wiring. Control and electrical wiring tampered. Malfunctioning or no functioning of controls. Boiler ruptured. Explosion in furnace. Loss of life. Damage to assets. Periodic test and verification of controls. Controls and wiring should no be tampered. Tampering with controls Lack of proper training to workers Improper operation of boiler may lead to boiler rupture. Explosion in furnace. Loss of life. Damage to assets. Only trained and authorized workers should have access. Operators should be properly trained. Poor maintenance Lack of maintenance policy an procedure. Poor or no training to workers. Fatal risk for workers and assets. Low operating efficiency and poor operation. Leads to high repair and replacement cost. Implement a well documented maintenance policy and procedures. Keep maintenance log. Condensate tank explosion. Improperly vented tank or vent too small. Vent may be trapped. Trapped vent has frozen condensate. Excessive tank pressure may lead to explosion. Loss of life. Damage to assets. Traps in vent line should be eliminated. Vent should be of full size. Explosion in furnace Inadequate pilot/igniter. Low pressure of oil or gas. Not correctly positioned. The nozzle may be too small. Improper setting of light-off. Damper. Plugged orifice. Delay in ignition or may not ignite the main flame. Fireside explosion. Fire. Boiler damage. Loss of life and severe injury. Damage to assets. Ensure periodic maintenance of pilot. Correct the pilot position, conduct periodic pilot verification test.

5 OPERATING HAZARD POSSIBLE CAUSES Ignition delayed. Pilot or igniter is not adequate. Fuel pressure may be low or fuel rate may not be sufficient. Excessive air rate. Low oil temperature. Water in fuel. LIKELY EFFECT Fire. Fireside explosion. Can damage the boiler. Loss of life and severe injury. Damage to assets. Ensure adequate pilot. Light-off fuel/aeration. Pilot turndown test. Excessive restart attempts should be avoided. Combustion air not sufficient. Lack of adequate air openings in the boiler room. Dirty combustion air blower. Combustion air blower running too slow or slipping. Setting of fuel/aeration not proper. Blockage in blower inlet or in outlet damper. Boiler gas passage may be plugged Delayed ignition. Combustion may be inadequate. Fireside explosion. Loss of life and severe injury. Damage to assets. Fire. Boiler damage. Enhanced emissions. Ensure adequate air to boiler room. Combustion air fans should be clean and running properly. Periodic inspection of air inlets and outlets, combustion controls, boiler gas passages, hot fuel gas passage, dampers and hot flue gas temperature. Combustion safety control tampered Lack of knowledge or poor operator training. Can lead to fireside explosion. Fire. Loss of life and serious injury. Damage to boiler and assets. Only authorized personnel should conduct maintenance. Operators should be properly trained in maintenance and operation procedure. Leaks in fuel safety shutoff valves. Defective valve. Foreign objects under valve seat. Fuel can flow to the boiler. Uncontrolled ignition of fuel. Fireside explosion. Loss of life and severe injury. Fire. Damage to boiler and assets. Periodic inspection of valves. Defective valves should be replaced promptly. Regular leak test and verification of valves operation. IMPLOSIONS Excessive negative pressure Flame out Damage to equipment. Serious risk of injury. Control equipment should be properly operated and should not be bypassed. MAINTENACE Equipment undergoing maintenance. Sudden starting of remotely controlled equipment. Release of fluid pressure. Electrical shock. Lock out/ tag out not followed, equipment not in zero mechanical state, or not in zero energy state. Can lead to severe injury or death of workers The equipment should be replaced in zero energy state and zero mechanical state. Comply with lockout and tag out procedures. Workers should be trained for alertness. Post warning signs.

6 OPERATING HAZARD POSSIBLE CAUSES Cleaning Neglecting safety procedures for maintenance cleaning LIKELY EFFECT Can lead to severe injury or death of workers Carefully follow all maintenance procedure cleaning. Provide appropriate protective clothing to workers. Regular cleaning and removal of ash, soot, slag etc can prevent excessive accumulation. Entering a confined or enclosed space such as furnace, ducts, drums, shell, gas passes, flues, tanks, bunkers, hoppers, tec. Can be extremely hazardous due to toxic or inflammable oxygen deficient atmosphere and hot material. Con lead to severe injury or death of workers Ensure sufficient ventilation for the fresh air. Conduct test for oxygen deficiency, toxic or inflammable gases before entering. Ensure adequate lights before entering an enclosed space. Follow all applicable safety rules. Airborne contaminants such as gases, fumes, vapors, dust and mist. Ventilation or exhaust not proper. Leakage. Can lead to sever injury or death of workers Ventilation or exhaust system should be in good working condition. Provide respiratory mask and protective clothing. Moving equipment or parts and fan blades in exposed condition Safety guards missing Can lead to severe injury. Ensure safety guards are installed. Loose clothing and long hair should be avoided. Congestion in work area Poor housekeeping. Risk of falls, slips and trips leading to injury. All equipment should have clear and unobstructed access. Maintain good housekeeping. Accidental opening of the access door. Closed door is not locked or bolted. Risk of bodily injury Ensure all access doors are locked. ELETRICAL Exposed/ naked electrical wiring Damaged or no insulation. Poor maintenance. Risk of severe electrical shock causing injury, burns or even death. Ensure all electrical wiring is secure and insulated. Exposed electrical boxes. Negligence Risk of severe electrical shock causing injury, burns or even death Ensure electrical boxes are covered Switch box opens without turning off powers. Safety catch damaged allowing opening without shutting off power. Risk of severe electrical shock causing injury, burns or even death. Safety catch should be repaired immediately.

7 Additional measures for boiler safety compliance Boiler licence, manual and log Obtain a boiler licence if the local law requires it. Keep manufacturers safety manual for all equipment accessible and handy. Keep and maintain a service log for each boiler. Boilers should be serviced by licensed companies/individuals. Location and access The boiler should be housed in a separate room away from the general production area. Ensure adequate ventilation in the boiler room. Ensure that no flammable or combustible materials are stored in the boiler room or next to it. Restrict the entry to the boiler area only to authorized personnel. Housekeeping Ensure good housekeeping of the boiler room. Do not allow dumping of waste or unnecessary articles in the boiler room. Keep floor drains clean, clear and unclogged. Safe operation Do not leave the boiler operation to a person who is not trained or qualified. The operator should ideally have a formal qualification and training to run a boiler of given capacity. Clear direction should be provided for start-up, running and shutdown procedures, blow down, high and low water conditions, and emergency procedures. If a boiler plant is started remotely and/or automatically without warning, workers must be alert to avoid that equipment which can be started remotely. The water for the boiler should be treated for hardness before using. Each boiler should have a temperature gauge.

8 Ensure easy access to ladders, runways and controls. Ensure sound boiler piping support, foundation and settings for all equipment. Piping systems including flow direction should be properly marked. Post piping diagram at the location. A fire boiler utilizes flammable and potentially explosive fuel. Fuel-piping connection should be of high quality using the correct gasket, bolts, thread lubricants and tightening torque to prevent leaks. Maintenance and risk prevention Implement an extensive preventive maintenance program. Gauge, control equipment pressure relief valves, pumps and valves, water quality and treatment methods, burner and fuel systems must be checked periodically to prevent hazards. All pipes and fitting should e well-maintained and in good condition. The boiler area has many heated surfaces causing risks of burns and other thermal hazards. Wherever possible, refractory and insulation should be used to reduce surface temperature. Protect the water supply to the boiler by installing an approved back-flow stopper. Promptly repair leaking steam, water, fuel and other boiler connections. Periodically clean and inspect exhaust venting, breeching and chimney to remove combustion gases. Conduct periodic boiler water analysis and chemical treatment to prevent corrosion, pitting and scale. Safety or relief valves should be tested by lifting the test lever at least once a year. High voltages exist in control panels and control components. Power must be shut off before these components are serviced. The boiler plant should have a documented lockout and tag-out procedure that is strictly enforced.

9 Workers training and PPE Workers must be trained in safe operation of the boiler equipment. The training should be a continuous process to emphasize the importance of safety. Wearing loose clothing and jewellery should be avoided in the boiler plant. Appropriate Personal Protective Equipment (PPE), such as respirators, ear plugs, guides, shields, or covers should be fitted in rotating equipment, mechanically automated devices, or electrically and pneumatically operated control components to prevent accidents. Fire Safety and First aid Ensure safe exits in the boiler room. Place an adequate number of suitable fire extinguishers in and outside the boiler room. Link the boiler room with the fire alarm system of the factory by installing a fire alarm switch/box. Place sand buckets near the boiler room to manage any spills. Place No Smoking signs in the boiler room in the workers language as well as in English. Place First aid kit just outside the boiler room. MOST COMMONTLY FOUND VIOLATIONs The factory does not have a valid/renewed boiler licence (applicable to large boilers) The factory does not have a maintenance log. Boiler operators do not wear the required Personal Protective Equipment (PPE) The boiler area does not have fire extinguishers, fire alarm and first aid box. Housekeeping in the boiler area is poor BEST PRACTICE The factory has implemented a written procedure for the safe operation and maintenance of boilers. Maintenance reports are documented, reviewed by management and kept in the file.